Steam generator lagging assembly including flashing and clip members



Aug. 29, 1967 N. D. JACOBS 3,338,004 STEAM GENERATOR LAGGING ASSEMBLY INCLUDING FLASHING AND CLIP MEMBERS Filed Dec. 15, 1964 INVENTOR. Norman D. Jacobs United States Patent Ofifice 3,338,004 Patented Aug. 29, 1967 3,338,004 STEAM GENERATOR LAGGING ASSEM- BLY INCLUDING FLASHING AND CLIP MEMBERS Norman D. Jacobs, Greensburg, North Canton, Ohio, as-

signor to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Dec. 15, 1964, Ser. No. 418,396 1 Claim. (Cl. 52-62) The present invention is directed to a fastener which facilitates the installation of metal lagging on the exterior of a steam generator wall enclosure, and more particularly to a fastener which is simple and inexpensive to fabricate and install and which cuts down substantially on field erection time and expense while at the same time permitting the lagging to be readily attached to structural framing of diverse arrangements and size.

In modern steam generators, the walls defining the combustion chamber or furnace generally include boundary walls of spaced upright fluid-cooling tubes exteriorly reinforced to withstand the furnace pressure by a buckstay system comprising structural steel buckstay assemblies spaced as required at several elevations along the upright portion of the wall forming tubes. Generally the exterior wall surfaces are insulated to minimize radiation losses, the insulation being applied to the space between the tubes and the inner flange of the buckstay. To protect the insulated surfaces from deterioration and spalling a wear surface is generally applied over the insulation, which wear surface at the same time provides a finished outer wall surface. Frequently, light gauge metal lagging is used to accomplish these ends. Inasmuch as the insulation material itself does not have the necessary structural strength to support the boiler lagging, and since the attachment of metallic supports to the wall tubes to carry the lagging would be thermally uneconomic, it has become common practice to support and secure the lagging to the wall buckstays. However, since the size of the individual buckstays of a steam generator buckstay system may vary depending on the physical arrangement of the system and the forces the buckstay is designed to withstand, the lagging support and fastening devices known in the prior art are such as to necessitate custom-forming of the supports and ties during the field assembly of the steam generator to insure a satisfactory lagging installation. Thus the prior art lagging fastener arrangements resulted in high cost and lengthy assembly procedures due to the variation in spacing dimensions between various adjacent buckstays.

Accordingly, the purpose of the present invention is to provide steam generator lagging fasteners or retainers which may be uniformly standardized for the walls of the steam generating unit regardless of the difference in spacing of the buckstays to which they are connected. Moreover, these fasteners may be quickly and simply assembled, thereby reducing the time and cost of installing the lagging on the walls of the unit. The fasteners here ,disclosed also will permit relative movement between the lagging and the buckstays to which they are fastened. This relative motion is necessary inasmuch as the buckstays generally move with the steam generator wall during start up and shut down as a result of thermal expansion of the wall so that the vertical spacing between adjacent buckstays will change from the cold position to the hot position so that the boiler lagging must accommodate this difference.

Accordingly the present invention provides a fastener arranged to attach a sheet member such that it will be in contact with the surface of a wall, the wall being restrained from horizontal movement by at least two horizontally extending stiffeners or buckstays which are arranged in vertically spaced horizontal planes, the fastener comprising a slotted clip connected at its closed end to one stiffener, the open end facing a stiffener in the next vertically adjacent horizontal plane, the sheet member having a flat surface parallel to the surface of the wall with one end of the sheet member being held in the slotted clip and the opposite end of the sheet member connected to the next adjacent stiffener.

More particularly, the present invention provides a steam generator lagging fastener or retainer which has a generally C-shape wherein the fasteners are arranged substantially normal to the plane of the wall enclosure and are connected at their closed ends to the lower flange portion or edge of one buckstay with the open ends facing a buckstay in the next lower horizontal plane.

The various features which characterize the invention are pointed out with particularity in the claim annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a pre ferred embodiment of the invention.

In the drawings:

FIG. 1 is a typical vertical section through a portion of a boiler furnace wall enclosure andlagging assembly incorporating the present invention;

FIG. 2 is a view of the wall, with a portion broken away, taken along line 2-2 of FIG. 1; and

FIG. 3 is a perspective view of the lagging fastener of the present invention.

Referring to FIG. 1, a portion of a typical furnace boiler wall enclosure 10 is shown composed of a plurality of vertically extending wall cooling tubes 12 arranged in a manner well known in the art. Insulating material 14 is disposed adjacent to the outer surface of the tube wall and is covered with a metallic lagging sheet 16 to form an exterior wall surface. Lateral movement of the wall, due to temperature induced thermal expansion and internal pressure, is restrained by horizontally extending buckstay beam members 18 which form the buckstay system associated with the wall which operates in a manner Well known in the art. The lagging 16 is a generally flat, thin sheet member that may have spaced ribs 27 to make the sheet stiffer and thus easier to handle and install. A plurality of L-shaped fasteners 20 are connected to buckstay 18 at spaced locations along the upper flange portion or edge of the beam as shown in FIG. 1. A flashing member 22 having a cross-sectional shape generally as indicated in FIG. 1 is connected, as by a plurality of self tapping metal screws 23 or other suitable means, to the upper outstanding leg of the L-shaped fasteners 20 with the lower portion of the flashing extending over the space between the uppermost part of the L-shaped fasteners and the flange of the buckstay 18. The flashing permits the protection of the portion of the outer surface of the insulation between the ends of the lagging 16 and the buckstay, which would otherwise be exposed. A slotted plate lagging fastener clip 24, see FIG. 3, which has a generally C- shape is attached, as by welding, to the lower edge of the flange of the next superjacent buckstay 18. A plurality of clips 24 are fastened to the buckstay at spaced locations along the lower edge thereof so that each sheet of lagging is held by at least two clips, as seen in FIG. 2. In the assembly, the clip is connected at its closed end to the lower edge of the flange of the buckstay with the open end facing the next lower buckstay, and with the planes of the clips being substantially normal to the plane of the wall. The lagging sheet 16, having a height somewhat less than the distance between the adjacent buckstays, is then positioned therebetween with the upper end of the sheet being inserted in the slot of clip 24 and being slidably retained therein. The lower end of the lagging sheet rests on the upper surface of the flashing 22, with the lagging sheet being held thereto by a plurality of self tapping metal screws 23. An upper flashing member 26 is then connected to the upper edge of the lagging sheet and overlaps the space between the upper edge of the lagging sheet and the lower edge of the buckstay flange.

Inasmuch as the lagging sheet is not rigidly connected to the fastener clip 24, but is free to slide within the slot in the clip, relative motion between adjacent buckstays is thus readily accommodated. Furthermore, since the fastener clip may be substantially elongated without interfering with its functioning the same size clip may be used throughout the steam generator regardless of the variations in the vertical distances between the facing edges of adjacent buckstays due to the varying sized buckstays used at different locations on the boiler. As a result the amount of custom fitting during the assembly of the lagging is practically eliminated with substantial reductions both in the cost and time required for lagging assembly. Furthermore, since the clips 24 may be spot welded to the buckstays in the field, considerable latitude is obtained in the spacings possible, permitting variations therein to meet the requirements at any location on the boiler. Furthermore, since the fastener clips of the resent invention can be readily manufactured before shipment to the boiler site the cost of the fasteners themselves may be substantially reduced.

While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the clam, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

A steam generator lagging assembly comprising in combination a vertical steam generator wall, a plurality of horizontally extending buckstays, said wall being restrained from horizontal movement by said buckstays which are arranged in at least two vertically spaced horizontal planes, a plurality of lagging fasteners each comprising a slotted plate clip having a generally C-shape, said clips being connected at the closed ends in horizontally spaced relationship along the lower edge of an upper buckstay with the open ends facing a buckstay in the next lower horizontal plane, the planes of said clips being substantially normal to the plane of said wall, and a lagging member having flat surface portions which are parallel to the outer surface of said wall at the upper end of the lagging member arranged to be slidably held in the slots of said clips, the lower end of said lagging member being rigidly connected to the upper edge of said next lower buckstay, and upper and lower flashing members connected to the upper and lower ends of said lagging member and overlapping the joints between said lagging memher and said buckstays.

References Cited UNITED STATES PATENTS 1,696,104 12/1928 Seqard 52-512 X 1,988,147 1/1935 Voigt 52-488 3,163,265 12/1964 Waite 52573 X JOHN E. MURTAGH, Primary Examiner.

FRANK L. ABBOTT, Examiner.

G. W. HORNADAY, Assistant Examiner. 

